Amy: What if you could find a roommate who was a scientist and already familiar and comfortable with your ways.
Sheldon: That would be ideal. If a person like that existed, I would sign on, no further questions asked.
Amy: Great. Here I am!
Sheldon: Wait. Here who is where?
Amy: Me. Aren't I your perfect roommate?
Amy: Think about it, Sheldon. I'm not a stranger, we're both intellectually compatible, I'm willing to chauffeur you around town, and your personality quirks, which others find abhorrent and rage-inducing, I find cute as a button. What do you think?
Amy: Tell me one reason why this isn't a fantastic idea.
Amy: See? You can't. I'm gonna go see if Leonard's room is big enough for my water bed.